English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

It is difficult to distinguish hadronic process from the leptonic one in$\gamma$-ray observation, which is however crucial in revealing the origin ofcosmic rays. As an endeavor in the regard, we focus in this work on the complex$\gamma$-ray emitting region, which partially overlaps with the unidentifiedTeV source HESS~J1858+020 and includes supernova remnant (SNR) G35.6$-$0.4 andHII region G35.6$-$0.5. We reanalyze CO-line, HI, and Fermi-LAT GeV$\gamma$-ray emission data of this region. The analysis of the molecular and HIdata suggests that SNR G35.6$-$0.4 and HII region G35.6$-$0.5 are located atdifferent distances. The analysis the GeV $\gamma$-rays shows that GeV emissionarises from two point sources: one (SrcA) coincident with the SNR, and theother (SrcB) coincident with both HESS J1858+020 and HII region G35.6$-$0.5.The GeV emission of SrcA can be explained by the hadronic process in the SNR-MCassociation scenario. The GeV-band spectrum of SrcB and the TeV-band spectrumof HESS J1858+020 can be smoothly connected by a power-law function, with anindex of $\sim$2.2. The connected spectrum is well explained with a hadronicemission, with the cutoff energy of protons above 1 PeV. It thus indicates thatthere is a potential PeVatron in the HII region and should be further verifiedwith ultra-high energy observations with, e.g., LHAASO.

GeV Gamma-ray Emission and Molecular Clouds towards Supernova Remnant G35.6$-$0.4 and the TeV Source HESS J1858+020